/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesInterface/Public/Online/SchemaTypes.h
Example: In the case of a lobby the backing service is capable of storing attributes for a lobby and a lobby member. There will be separate service descriptors for lobby and lobby member where each will list the attributes available to be set as well as the types of data each attribute can store. The lobby implementation refers to the attributes names in the service descriptor directly when handling the serialization of attributes.
typedef [FName](API\Runtime\Core\UObject\FName) FSchemaServiceDescriptorId